Electric clock



Patented Mar. 6, 1928.

UNITED STATES PATENT OFFICE.

ELECTRIC CLOCK.`

Application filed August 6, 1924, Serial No. 730,449, and in Great `ritain August 10, 1923.

ln the specification tiled with my United States Patent No. 1,493,279 l have .described lished by the time-keeping element, the

swing of the latter is sustained mechanically by energy stored in a spring orsprings or weight 'through the agency of a movable element of the electromagnetic circuitbreaker, which latter controls the operation of the time-indicating mechanism, and said movable element, consequent on the movement of the time-keeping element from one operative position to another, engages a springer weight and energizes it to impart a sustaining impulse to the time-keepingelement, or the movable element of the circuitbreaker may be provided with a light spring or the like which is brought into contact with the time-keeping element and imparts to it the required sustaining impulse.

The invention is illustrated in the accompanying drawings, wherein Fig. 1 is a diagrammatic representation ot the circuit arrangement ot an electric clock operating as described in the allers-mentioned patent specification; Figs. 2 and 3 are respectively' a plan view and a sectional plan showing on an enlarged scale one construction of spring contact used in the control circuit of the clock; Figs. fle-8 inclusive are diagrammatic views in elevation; and Figs. 42h55 inelusivey are corresponding views in plan showing the relation of the pendulum and the spring contacts ot the control circuit for various phases of the swing of the pendulum.

Referring to Fig. 1 the pendulum or timing element 1, which is pivoted at 2, carries a pair oi contacts 27, 28, one on either side, which cooperate with contact springs 27', 28' connected respectively by leads 5 and 6 with coils 7, 8 of an electromagnetic circuit reverser and with the ixed contacts 9, 10 thereof. A light spring contact arm 11 carried by a polarized armature 12 is moved into flexed engagement with contact 9 or 10, according as the coil 8 or the coil 7 is energized. The spring contact 11 is connected with one terminal ot a battery 13, the other terminal oit which is connected through lead A with a time-indicating device 15 and thence, through lead 16, with the pendulum suspension which in turn is electrically connected with the contacts 27 and 28.

Assuming the contact arm 11 of the circuit reverser to be in the position shown in flexed engagement with contact 9 and the pendulum l to be swinging'from left to right, when contacts 27 and 27'engage a circuit will be established from battery 13 through spring contact 11, contact 9, energizing coil 7, lead 5, contacts 27', 27, lead 16, time-indicating device 15 and lead 14 back to battery. Consequent upon the current in coil 7 the armature 12 will be attracted towards the core of this coil and away from the core of coil 8, and the spring contact arm 11 will consequently break the circuit at contact 9 after a timelapse determined by the inertia of the armature and the degree 'of tlexure of spring 11, and be thrown over against contact 10 to establish another circuit trom battery 13, through contact arm 11, contact 10, coil 8, lead 6, contacts 28', 28 (when, lupon the return swing of the pendulum, these are brought into engagement), lead 16, time-indicating.;

device 15 and lead 14 back to battery.

It will be seen that the establishment of the control circuit by the pendulum, either through contacts 27, 27', or 28, 28', shifts the` circuitl breaker or reverser trom one operative position to the other and the current which ei'iects this also traverses the energizing coil of the time-indicating mechanism, which may be of any suitable step-by-stcp electrically operated kind. Also, since upon each swing ot the pendulum the contacts 27, 27 (or 28, 28') are in engagement during quitev a large proportion of each swing, it follows that they will still be in contact at the moment that the circuit breaker or reverser is thrown over from one operative position to the other, and consequently the actual breaking ot the circuit to interrupt the current flow takes place, not at the pendulum or control contact, but always at the. circuit reverser contact.

llvlhile in some respects it is immaterial whether the pendulum contacts 27, 28 are rigid and the lined contacts 27 28 yield ing or conversely, the former arrangement is preferred as it aillords convenient means tor applying mechanically to the pendulum a periodic sustaining impulse oi` constant value. il convenient torni of yielding contact tor the purposes contemplated is shown in Figs. 2 and 3, wherein is a metal tube having one or more longitudinal slits at its inneil end which lits 'friction tight over a boss 25 on a crank arm 26 iulcrumed on a terminal block suitably connected in the control circuit. inside the tube 24. is a spring contact wire 23" preferably having a contact surface ot a nonoxidizing character, the outer or ifree end oi which exposed by a portion of the tube 2d being cut away as indicated at 2li', wille the inner lined end is rigidly secured to the tube 2d. 'lhe distance oit the spring contact 27 trom the central position et the pendulum can be adjusted by turning the crank arm 26 about 'liulcrum, any suitable means being provided to secure the contacts in the positions to which they have been adjusted.

The contacts 27, 28 on the pendulum may consist of rigid platinum wires arranged substantially at right angles to the spring Contact wires 27 28 (Figs. llt-8a). As the pendulum swings outwardly on either side trom the central position the contact elements on that side engage and establish the circuit oi coil 'i' or coil 8 as the case may be. The spring 27 or 28 is flexed by the pendulum during the remainder of the outward swing and reacts on the pendulum during the corresponding part of the inward swing, the energy stored in the spring by its ilenure being thus returned to the pendulum. By applying tension by external means to the spring 27, :tor example, so that it acts on the pendulum over a longer distance during the inward swing than that over which the pendulum acts upon the spring to energize it during the outward swing, more energy is imparted to the pen dulum upon the inward swing than is absorbed from the pendulum upon the outward swing, and it is thus possible by means of this residuum of energy to compensate the resisting forces opposing the movement ci the pendulum and thereby maintain the amplitude ol' its swing. `With this object the spring contact 27 is displaced so as to be partly tensioned or energized, after the pendulum on its inward swing has moved away from it, by means of a movable member, for example a pin 29 (Figs. l., 4-88), attached to the armature of an electromagnetic device included in a circuit established by the operation of the contacts 27, 27 or Q8, 28. rlChis electromagnetic device may conveniently be the same device as that accuses which operates to break the energizing circuit, viz, the circuit-breaker 7, 8 (F ig. l). The changes in position of the cooperating` parts are illustrated in Figs. lil-8a. ln Figs.

Ll and 4a the pendulum l is shown in the t intermediate position moving trom right to left and the pin 29 in its inoperative position in so iar as regards the iiexure of spring contact QT. ln Figs. 5 and 5 the pendulum has moved over to establish contact Awith the spring contact 27', displacing the latter outwardly to a delinite extent which can be adjusted by appropriate means.

'llhe pendulum on its return swing towa ds the right lirst establishes contact with the spring 27 in its displaced position, as shown in Figs't and G, thereby again energizing electromagnet 7 and consequently shifting the armature l2 baclr into its other operative position, so that the pin E29 is withdrawn into its inoperative position, as shown in Figs. 7 and 7, The pendulum continues its outward movement to the right, still further flexing the spring 27, until it reaches its limiting position as shown in liigs. 'l and 7, in which position the displacement ot the spring 27 is a maximum. @n the return inward swing of the pendulum the spring ollows up the pendulum overV the complete range of its iiexure, since the pin 29 has been retracted and is no longer in a position in which it can arrest the return of the spring 27 to its initial position, as shown in liigs. 8 and 8a and? and 7a. lt will bessen therefore that during the return or inward swing of the pendulum the tension spring '27 acts through an additional range upon the pendulum as compared with the range oi engagement on the outward swing, namely over the distance indicated by the diiierence in the position of the spring 27 as shown in Figs. 5, 5 and 6, 6a, and its position as shown in ligs. l and a. Y

By such a method of sustaining the osoillations oit the timekeeping element the amplitude vand time-keeping are entirely independent of variations, :trom whatever cause, in the electric energizing circuit. Further, the amplitude of swing can be readily adjusted by altering one or both oli the limiting positions of the spring acting upon the time-keeping element.

Having thus described the nature ot the saidinvention and the best means l know ot carrying the same into practical eilect, l claim i l. An electrically driven cloclr, comprising a time-indicating mechanism, an oscillating time-keeping element mechanically Sil lltl

llo'

lilil separate from the time-indicating mechanism, an electromagnetic device included in a circuit controlled by the time-keeping element, a spring external to the oscillating time-keeping element and arranged to be deiected and energized by the latter towards the end of an oscillation, and an element actuated by the said electromagnetic device and ope ating to deiect and energize said spring prior to its engagement by the oscillating time-keeping element, said electromagnetically actuated element beingiwithdrawn from engagement with said spring during the period of engagement therewith ot the oscillating time-keeping element.

2. An electrically driven clock, comprising a time-indicating mechanism, an oscillating time-keeping element mechanically separate from the time-indicating mechanism, an electromagnetic circuitbreaker included in a circuit controlled by the timekeeping element and itself controlling the operation of the time-indicating mechanism, a ixed spring contact external to the oscillating time-keeping element and arranged to be engaged by the latter' towards the end ot' a swing thereof, and a movable element. on the electromagnetic circuit breaker operating to `detlect and energize the said spring contact prior to its engagement by the oscillating time-keeping element.

3. An electrically driven clock, comprising a time-indicating mechanism7 an oscillating time-keeping element mechanically separate from the time-indicating mechanism, a control circuit arranged to be closed by the operation ot the oscillating time-keeping element, an auxiliary circuit interrupter operating to open the said control circuit, a spring arranged to act on the time-keeping element during part of its oscillation, electromagnetic means for intermittently tensioning said spring comprising two coils alternately brought into the energizing circuit and a single battery supplying current alternately to said coils.

In testimony whereof I have signed my naine to this specification.

CHARLES EDMOND PRINCE. 

